The present invention relates generally to spray deposition, such as thermal spray deposition, and more particularly relates to systems and methods for producing fine line features using spray deposition.
It is generally known that thermal spray deposition is an effective technique for the fabrication of multi-layer devices which have various layers with a variety of physical characteristics and properties. An advantage of thermal spray deposition is that it is generally a one-step process which combines melting, quenching and consolidation into a single operation.
As described in U.S. Pat. No. 5,301,863 to Prinz, using spray deposition techniques in conjunction with a predefined mask, multilayer articles can be fabricated on a substrate. However, the typical plume from a thermal spray torch results in over spray and high temperature impingement on the mask. Also, since the mask is mounted on the substrate, there are limits on the geometry of the underlying substrate on which such circuits can accurately be fabricated. In addition, the mask and any unwanted deposit material must be removed from the surface of the substrate prior to fabricating subsequent layers. This requires additional fabrication steps and equipment.
It would be desirable to provide a system for fine line spray deposition of materials, such as conductors and insulators, which does not require a predefined mask and which offers reduced exposure to the high temperature plume of a spray torch.
It is an object of the present invention to provide a system for fine line spray deposition.
It is a further object of the present invention to provide an apparatus for fine line spray deposition which reduces thermal impingement on the surface of the substrate.
It is another object of the present invention to provide a method for producing multilayer structures, such as electronic circuits, using a thermal spray deposition process without requiring a mask in contact with the substrate.
A method for depositing a fine feature on a substrate using spray deposition in accordance with the invention includes generating a stream of material from a spray source, passing a portion of the stream through a collimator spaced from the spray source, passing the portion of the stream through an opening in an aperture member spaced from the collimator and supported above the surface of the substrate, and moving one of the substrate or aperture member to define the feature on the surface of the substrate.
Preferably, the aperture member is dynamic and the method also includes the step of adjusting the opening in the aperture member in accordance with a feature to be generated. For example, the aperture member can include a number of intersecting members which define an opening over the substrate where the size of the opening can be altered by changing the relative position of the members. Alternatively, an aperture member cutting station can be provided to generate the desired aperture opening prior to advancing the opening over the surface of the substrate.
By repeating the process with materials having various electrical properties, such as conductive, resistive, dielectric and insulative materials, multilayer electronic components and sensor systems can be directly printed on the surface of a substrate.
A system for fine feature spray deposition in accordance with the present invention includes a substrate platform for supporting a substrate on which the features are to be deposited. A spray assembly is provided which includes a spray source for providing a stream of material to be deposited on a substrate, a collimator which is positioned in a path of the stream from said spray source and an aperture assembly, which is positioned downstream of the collimator with respect to the spray source and above the substrate platform. The aperture assembly defines at least one opening to pass at least a portion of the stream of material onto a surface of the substrate. A drive mechanism is provided which is coupled to at least one of the spray assembly and the substrate platform for inducing relative motion there between. A controller is coupled to the spray assembly and the drive mechanism to control the relative motion and the stream of material.
In certain embodiments, the spray assembly can be fabricated without the use of a collimator, with a simplified collimator design or by replacing the collimator with an additional apperture spaced apart from the first aperture.
In one embodiment, the collimator is formed with a first wall section and a second wall section which converge in a V-shaped arrangement and define an opening at an apex of the V-shaped arrangement.
The collimator can include first and second collimator members in a spaced relationship with respect to one another. For example, the first collimator member can be formed with a first wall section and a second wall section converging in a V-shaped arrangement and defining an opening at an apex of the V-shaped arrangement and the second collimator member can be formed as a frustoconical member having an opening in substantial alignment with at least a portion of the opening in the first collimator member.
The aperture assembly can be formed with a supply reel, an elongate strip of flexible aperture material having at least one opening defined therein and engaged on the supply reel, and a take-up reel for receiving the aperture material. The supply reel and take-up reel are positioned to extend at least a portion of the aperture material over the substrate platform. A rotational drive assembly is operatively coupled to at least one of the supply reel and the take-up reel to advance the aperture material with respect to the substrate platform. The aperture material can be formed with a number of openings arranged in repeating patterns along the length of the aperture material.
In another embodiment, the aperture assembly includes a supply reel having a first supply reel portion and a second supply reel portion which are axially aligned and axially displaceable. A first elongate strip of flexible aperture material is engaged on the first supply reel portion and a second elongate strip of flexible aperture material is engaged on the second supply reel portion. A take-up reel is provided for receiving the aperture material. The take-up reel has a first take-up reel portion and a second take-up reel portion which are mutually axially aligned and axially displaceable. The supply reel and take-up reel are positioned to extend at least a portion of the first elongate strip of flexible aperture material and the second elongate strip of flexible aperture material over the substrate platform in a substantially parallel relationship to define an opening therebetween. A rotational drive assembly is coupled to at least one of the supply reel and the take-up reel to advance the aperture material with respect to the substrate platform. A displacement drive assembly is operatively coupled to the supply reel and the take-up reel to control a spacing between the first elongate strip of flexible aperture material and the second elongate strip of flexible aperture material.
Preferably, the aperture assembly includes a first aperture sub-assembly and a second aperture sub-assembly, each formed substantially as described above, and being substantially orthogonally aligned over the substrate platform.
The drive mechanism of the system can take on several forms. For example, the drive mechanism can be an x-y drive table coupled to the substrate platform, spray assembly or both. Alternatively, the drive mechanism can include a robotic arm operable in the x, y and z directions which is coupled to the spray assembly, substrate platform or both.
The spray source can take the form of a combustion spray torch, a plasma spray torch, a detonation gun, high velocity oxygen fuel (HVOF) spray gun, arc spray, a cold spray gun and the like.
To enhance the rapid prototyping capability of the system, a CAD interface can be operatively coupled to the controller to translate drawing files from a computer aided design system to instructions for the CPU to control the spray assembly and drive mechanism.
In yet another embodiment, the aperture assembly can include an aperture cutting device, such as a laser, which is operatively coupled to the controller for forming the opening in the aperture assembly.